Struggling choosing and buying packs (ranking and cheap options)

I find that buying packs when they are 50% off is way cheaper than buying them in a bundle. Also, I'd suggest to buy the packs you're interested in over a period of time, rather than all all the same time, starting with the ones you feel pretty sure you will like and will bring the most fun content for you to play with.

My first purchase immediately after I got the base game was a bundle consisting of Season, Snowy Escape and Nifty Knitting. It was a great combination in my experience because they really go very well with each other.

Here is my very personal ranking of the packs you are considering buying:

1. Cottage Living
2. Snowy Escape
3. Get Together
4. Parenthood (Game pack)
5. Discover University
6. City Living
7. Tiny Living (Stuff pack)

Cottage Living gets a first place for me, but that's because even before it was announced, I was already playing farming and creating cottages. So It was a must for me. The world is very pretty and quaint, and if you like the countryside you'll fall in love with it. If you don't like the countryside and prefer more urban settings, it might be boring to you. There's a lot of gameplay revolving around farming, raising animals, interacting with small wild creatures, living in a close-knitted community, etc. If these things are appealing to you, go for it! :-)

I put Snow Escape in 2nd position. I really like the world (Mt Komorebi) and the winter sports skills (snowboarding, skiing, mountain climbing). The world is very charming to explore, including all the hikes and the fact you can swim in the river. I love mountain climbing expeditions. I don't care about the festivals.

Get Together is technically all about clubs, but this is in fact a feature I don't really care very much about. What I love about this pack is the new world, Windenburg - which is absolutely my favourite one. It's the most European of all the Sims worlds and it's pretty fabulous and unique. I love the build-mode items. In spite of my underuse of the clubs system, they have a lot of potential and really enrich the game.

Parenthood is very good if you enjoy playing families, because it enriches interactions between parents and children. It turned children and teens into more interesting Sims to play, for me. Prior to buying this pack I never played kids because they weren't as interesting as young adults. But this pack adds some special new elements such as character values that can be developed, and I really like that feature, as it contributes to developing Sims with more defined personalities.

Discover University is another pack that brings a very beautiful world. I don't care too much about sending my Sims to University, as sometimes the gameplay involved in earning a degree gets really boring, but I do love the world. In fact I've pretty much removed all prebuilt lots and I've filled it with buildings that have nothing to do with university and I use it as a normal world.

City Living: I'm not a huge fan of this pack. I don't particularly like the new world and I don't care about the festivals. But you might like it more than I do if you prefer an urban setting to the more common suburban setting of the other worlds. It also features apartments.

Tiny Living: I like the concept but I rarely, if ever, use content from this pack.

Can't really be much help with ranking as these are all some of my least favorites, but if you want to save money CDKeys is the best bet. I use it all the time and I've used it for most the packs and never had an issue. I've found that some times they're selling all of the expansions for as little as 10 bucks each so it's definitely worth shopping there rather than paying EA's extortionate prices

There are regular Origin/Steam sales and build your own bundles, so I do recommend to wait for those. However, if you do go the code route, just do your research. If it looks too good to be true, it probably is, and a quick search will find you some horror stories. As a general rule, I do not buy from private sellers for digital content, or sites that buy codes from private sellers for resale, but codes are definitely a legit route to take.

If you want a recommendation for discount games, I personally recommend Humble Bundle. It does all sorts of stuff, including preorders, and for charity. I do not know how the discounts always compare, but I have heard its praises sung to the high heavens.

Also, quickly, my favs:
1. Cottage Living
2. Snowy Escape
3. Discover University
4. City Living
5. Parenthood
6. Get Together
7. Tiny Living

All packs have potential to be worth it depending how you play and how much of the pack you think you will use. I do recommend waiting for a sale though if possible because (IMO) no pack is worth the full price except a small select few.

1. Cottage Living: It's new and likely won't be on sale for a little while, however this is one that I would (and did) pay full price for and I have no regrets. The oversized crops and the animals add so much to my style of game play and the CAS is adorable. BB is lacking a bit but what is there is really well done and there are a ton of beautiful items in the debug.
2. Snowy Escape: I like building and I use this pack daily. Mt. Komorebi is beautiful but a lot can only be done in that world so the pack is game play limited in that way. Again, adorable CAS though.
3. City Living: Apartments are fun for a minute, comes with karaoke though which I use in almost every bar build now. CAS is pretty and the festivals add some extra flavour to the game play. I use the yard sale table constantly though and I couldn't imagine my game without it anymore for Rags to Riches style game play.
4. Get Together: Clubs are useful. That's about all, I don't use anything in this pack often and I'm glad that I waited for a sale for this.
5. Tiny Living: The BB and CAS are super cute. I needed to have that murphy bed. I do not regret paying full price for this, but now that it's a bit older, a sale price might be better. We have a lot of similar CAS in other packs now since the release of this one.
6. Discover University: I could have skipped this pack. Regret paying full price. The CAS and BB is great. University game play is a boring chore (IMO) and there's no replay value here (again my opinion). The boost that you get to the career and the time that it takes and the boring grind through just isn't it for me. The only reason this pack isn't dead last is because I do use the clothes, hair and BB almost daily.
7. Parenthood: I used the counters often but that's about it, and now that more packs have other counter options, I use them less. Some cute game play added with the pack but the messes the children make killed the pack for me. It's constant and you can't turn it off. Prepare for all of your community lots to be destroyed or to spend half the time that your sim is there just mopping up after the neighbourhood brats.